Sintered metal containing titanium carbide particles and method for making same

ABSTRACT

The metal part is comprised of a powdered metal mixture which is briquetted under pressure into a desired shape. The mixture includes about 0.25 to 60 percent by weight ferro titanium powder and about 0.1 to 10 percent by weight carbon with the remainder being substantially iron. The briquette is heat sintered to at least approximately 2000*F forming extremely hard titanium carbide particles measuring greater than 70 on the Rockwell C scale. The size and quantity of the titanium carbide particles vary with the percentage of ferro titanium addition and its mesh size.

[4.51 Nov. 26, 1974 1 SINTEREI) METAL CONTAINING TITANIUM CARBIDEPARTICLES AND METHOD FOR MAKING SAME [75] Inventor: Kenneth E. Kueny,Muskegon,

Mich.

[73} Assignee: Sealed Power Corporation,

Muskegon, Mich.

[22] Filed: Feb. 26, 1973 [21] Appl. No.: 335,709

[52] US. Cl 29/1827, 29/1828, 75/200, 75/203, 75/204, 75/227 [51] Int.Cl 1322f 1/00 [58] Field 011 Search 75/203, 204, 227, 200;

[56] References Cited UNITED STATES PATENTS 1,977,361 10/1934 Taylor eta1. 75/204 2,369,211 2/1945 Clark 75/204 3,167,428 H1966 Globus 75/2043,591,349 7/1971 Benjamin 29/1827 OTHER PUBLICATIONS Schwarzkopf et a1.,Cemented Carbides, The Macmillan Company, 1960, pp. 94 TP770S3.

Primary ExamineF-Benjamin R. P'adgett Assistant Examiner-3. HuntAttorney, Agent, or Firm-Price, Heneveld, Huizenga & Cooper 5 7 ABSTRACTThe metal part is comprised of a powdered metal mixture which isbriquetted under pressure into a desired shape. The mixture includesabout 0.25 to 60 percent by weight ferro titanium powder and about 0.1to 10 percent by weight carbon with the remainder being substantiallyiron. The briquette is heat sintered to at least approximately 2000Fforming extremely hard titanium carbide particles measuring greater than70 on the Rockwell C scale. The size and quantity of the titaniumcarbide particles vary with the percentage of ferro titanium additionand its mesh size.

18 Claims, No Drawings SINTERED METAL CONTAINING TITANIUM CARBIDEPARTICLES AND METHOD FOR MAKING SAME BACKGROUND OF THE INVENTION Thisinvention relates to metal parts, and more particularly to a heatsintered metal part having extremely high wearability.

Hardened iron parts such as iron castings have been the mainstay foryears in a host of apparatus and machinery environments where excessivewear and potential failure occurs not infrequently. Evaluations showfrequent loss of hardness in these parts to a detrimental extent. Severeloss of hardness is believed to be caused by excessive superficial heatgenerated by direct metalto-metal contact of the parts. Such contact isgenerally caused by lubrication breakdowns occurring in a variety ofdifferent environments.

Recently, as a result of continual investigation into ways and means forproducing a longer lasting higher wearing metal part at reducedeconomical expenditures, the production of metal parts by briquettingand sintering powdered metal has shown promise. The economicaladvantages in utilizing powdered metal parts is significant. However,adequate hardness and wearability have been a constant problem utilizingthis method. Adequate wearability has been unobtainable to date in apowdered metal part. Thus, there is a need in this art for a metal partproduced by heat sintering powdered metals, the resultant'product ofwhich provides acceptable wearability.

SUMMARY OF THE INVENTION In accordance with the invention, an iron basedmetal part having exceptional wearability is obtained. The component ismade by sintering an iron based powder to which has been added about 0.lto 10.0 percent by weight carbon and about 0.25 to 60 percent by weightferro titanium. The component contains titanium carbide particles havinga hardness of greater than 70 on the Rockwell C scale.

The part is formed by mixing an iron powder and carbon with a ferrotitanium powder addition. The mixture is briquetted in a press into adesired shape and then heat sintered to at least approximately 2,000Fforming the titanium carbides. A commercial grade ferro titaniumcontaining 70 percent titanium works quite well with the particle sizevarying from 40 mesh and down to 325 mesh or even smaller. Wheredesired, the mixture of iron powder, ferro titanium and carbon cancontain other alloying elements added to the basic mixture. The additionof these other alloying elements however is not essential to theinvention defined herein.

The resultant part provides a metal with extremely improved wearabilityover anything known within the art. The wearability of the resultantmaterial is on the order of 40-50 times better than the materialscurrently being used in industry today. The process is both simple andextremely economical compared to present methods utilized in the art.

-DESCRIPTION OF THE PREFERRED EMBODIMENTS Generally speaking, thepresent invention provides a heat sintered powdered mixture which coactssynergistically to provide a metal part having physical propertiesexceeding that of presently used metals at significantly reduced costs.

The significant steps utilized are to mix in controlled amounts iron,carbon and ferro titanium powders. The controlled amounts of the mixtureby weight is about 0.1 to 10 percent carbon and about 0.25 to 60 percentferro titanium. The remainder is preferably substantially iron althoughthe presence of other metals is permissible, the significance of whichwill be described hereinafter. The mixture is pressure compacted(briquetted) into a desired shape and heat sintered to at leastapproximately 2,000F.

The ferro titanium powder preferably utilized in accordance with theinvention is a commercially available grade containing about percenttitanium powder with a particle size varying from 40 mesh and down to325 mesh or less. The ferro titanium powder used melts betweenapproximately 2,000-2,'0l2F and a significant aspect of the process isthat in the sintering operation, the ferro titanium actually melts anddissolves some or all of the available carbon in the surrounding matrixto form titanium carbide particles. These titanium carbide particles areextremely hard particles ranging upwardly from 70 on the Rockwell Cscale. Generally the range has been between 70-90 on the Rockwell Cscale using a micro hardness tester. The resultant formation of thesetitanium carbide particles forms a very hard wear resistant metal.Extensive testing indicates improved wearability on the order of 40-50times better than materials currently used in the industry today and farsuperior to any previously known powdered metal parts. Based on presenttest results, 1,000 hour test 'will yield less than 0.002 inch wear.

The size and quantity of the titanium carbides vary with the percentageand size of the ferro titanium addition. While the mesh size of the ironpowder is not of any particular significance in this regard, standardcommercial sizes on the order of 40 mesh and down have proven to workextremely well. Higher mesh sizes however will work.

Turning to the basic mixture itself, a number of tests have beenconducted utilizing various amounts by weight of the iron, carbon andferro titanium powders. These tests are set forth in detail below.Greater ranges than presently tested however should work equally well.

One of the more significant aspects of my invention is the synergisticresult of mixing, briquetting and heat sintering the ferro titaniumpowder with controlled amounts of carbon. While the preferred base isiron, other alloying elements should work equally well although theywill change certain of the characteristics of the method and resultantmetal part. The use of other alloying elements than iron has a largebearing on many factors not dealt with in detail herein. Two suchfactors of significant interest are increased costs of the powder itselfand increased melting temperatures required depending on the mixture.Elevated temperature requirements, of course. also increase the costfactor exponentially.

Regardless of the alloying element utilized however it is thesynergistic result of heat sintering a ferro titanium powder with carbonin the surrounding matrix which produces a most unusual resultant metala ferro titanium powder with carbon in the surrounding matrix whichproduces a most unusual resultant metal part over any presently known atcomparable economical input.

As little as 0.25 percent by weight ferro titanium powder is believed tobe adequate. Due to present costs The ferro titanium addition utilizedin samples 1 and 2 had a mesh particle size of 40 down to 325 while thatutilized in samples 3-5 had a mesh size of 325 and smaller. The ferrotitanium powder utilized is available of commercially available ferrotitanium powder, a 5 from Chemalloy Company Inc., Bryn Marr, Pa. 19010practical limit of 60 percent by weight ferro titanium r r as mm r i l qality ferro i anium powder powder is imposed due to present competitiveaspects p ifying per cent grade and mesh Size. The 09 perof the generalindustrial community. However, higher Cen Ca bon materials were madefrom Hoeganaes Anamounts will work in unusual circumstances where costchorsteel 1000 base iron powder available from H0- is not a factor.Regarding the carbon content, a particu- 10 eganaes Corporation,Riverton New Jersey, while the lar range by weight of about 0.1 to 10percent is envi- 1.7 percent carbon materials were made from Quebecsioned since lower amounts wont produce enough tita- Atomet 28 base ironpowder available from Quebec nium carbide particles and higher amountspresent e a Powders having an Outlet in Southfieid, problems inbriquetting and other related strength fac- Michigan. The heat sinteringcycle for samples l-5 tors of the resultant metal part. were identicalto that described previously with regard to example 1.

. EXAMPLE 1 Samples l-5 were tested in an Alpha Model LFW-l As aspecific example, a powdered mixture of the fol-' Friction and WearTesting Machine available from the lowing percentages by weight werethoroughly mixed Dow Corning Company. Various ones of each sample bystandard procedures in this art: 5% ferro titanium; were tested againsta 4620 C ring having a minimum 0.9% carbon; 2.0% copper; and 92.1% iron..The mesh hardness of 58-on the Rockwell C scale and a hardensize of theferro titanium powder was from 40 down to bl ir i h vi a minimumhardness of 55.00 on 325 and the iron powder was from 80 mesh and down.the Rockwell C scale. Each test lasted approximately A commerciallyavailable iron powder was used which 23.3 hours subjecting the sample toapproximately included the carbon and copper. The mixture was com-275,000 cycles, the Model LFW-l operating at 197 cypr e y a n nti nal prn a ylin r ricles per minute. In addition to the testing of samplesqueue having a diameter of inch and a length of 2 l-S, a test was alsoconducted using a conventional e The Press Utilized developed PP sampleof hardenable iron presently being used today, mately 36 tons per squareinch.- for comparative purposes. The hardenable iron sample Thebriquette WaS heat sintered for 6.0 hours. It was used had a sizecomparable to that of samples 1 5 and gradually heated fromapproximately 80F to 2,10 a minimum hardness of 55.0 on the Rockwell Cscale in 2 hours and maintained at approximately 2,1000]: for therebyexceeding the overall hardness of the test sam- 3 Period of l hourit wasCooled gradually w ples. The results are tabulated in the followingtable. to F Over 3 Period of 3 hours- After complete Samples l-S are thefive previously referred to samples ing to room temperature, resultantmetal P was while sample 6 is the comparative hardenable iron testtested for wearability. Present test indications predict Th wealfi re ii volume 1 i bi facial wear Of less than ll'lCh after test inches timesten to the negative six powen hours which is well within acceptablelimits.

The presence of copper in the foregoing example was arbitrary in thatthe particular commercial grade iron 40 powder included it. The presenceof other alloying elesample gfg g x f fig g ments does not affect theoverall unique characteristics of the invention as illustrated by thepresence of molyb- 1 61 denum in other examples set forth below. Minorimpu- 2:; 2 2:3 7 5 -rities such as phosphorous or sulphur also do notaffect 2 219.2786 28] 8 5 8355 3 the method or resultant art.

in order that those skill d in the art may have a better 6 368 7 284'0understanding of some of the ranges of controlled amounts of the presentinvention, the following sam- The foregoing table indicates a totallyunexpected ples were made up in accordance with the invention improvedwearability over what is in use today from a and subsequently tested formicro examination. The minimum factor of about 5 to l to as high as 94to 1. percentages listed are by weight of the powdered mix- The resultsare submitted as being significant especially ture which wassubsequently briquetted in a 36 ton in view of present day art and theheretofore unsuccesspress and heat sintered. The weight given is ingrams, ful search for an acceptable powdered metal part. thedisplacement in milliliters and density in grams per In production, themetal parts made in accordance cubic centimeter. The hardness listedindicates the with the invention would be made during briquettingoverall hardness of the sample on the Rockwell B scale very close totheir final desired geometry thereby reafter sintering. quiring aslittle machining as necessary after sintering.

Sample %C %Cu %Mo %FeTi Wt. Vol. Den Hardness Appropriate dies could bemade for utilization in the pressing step.

ltshould be appreciated that after sintering, the metal part may besubjected to other standard heat treating practices such as carbonitriding, flame hardening, induction hardening, salt bath, throughhardening, etc.

It is conceivable that certain minor variations from the specificcompositions noted may be made within the concept presented. Theinvention is intended to be limited only by the scope of the appendedclaims and the reasonable equivalents thereto.

The embodiments of the invention in which an exclusive property orprivelege is claimed are defined as follows:

1. The method of forming a metal part comprising the steps of: preparinga mixture of powdered material having about 0.25 to 60 percent by weightferro titanium and about 0.1 to percent by weight carbon the remainderof said powdered material being substantially iron based powder;compacting said mixture and heat sintering said mixture above themelting temperature of the ferro titanium powder whereby the ferrotitanium melts and dissolves available carbon in the surrounding matrixto form titanium carbide particles.

2. The method according to claim 1 wherein said ferro titanium powderprior to heat sintering has a mesh size of 40 or less.

3. The method according to claim 1 wherein said ferro titanium powderprior to heat sintering has a mesh size of 325 or less.

4. The method according to claim 1 wherein said mixture contains carbonin the range of about 0.5 to 1.5 percent by weight and ferro titanium inthe range of about L0 to 10 percent by weight.

5. The method according to claim 1 wherein said compacted mixture duringsintering is maintained at or above 2,000F for a period of approximatelyone hour.

6. The method according to claim 1 wherein said compacted mixture isheat sintered to at least 2,100F.

7. The method according to claim 6 wherein said compacted mixture duringsintering is maintained at or above 2,l00F for a period of approximatelyone hour.

8. The method according to claim 1 wherein said compacted mixture isgradually heated to about 2,100F over a period of about 2 hours;maintained at about 2,l00F for a period of about 1 hour; graduallycooled to about 825F over a period of about3 hours and then cooled toambient temperature.

9. The method according to claim 1 wherein said compacted mixture isheat sintered to at least approximately 2,000F.

10. A metal part comprising titanium carbide particles with a hardnessof or more on the Rockwell C scale and formed by the steps of: preparinga mixture of powdered material having about 0.25 to 60 percent by weightferro titanium and about 0.1 to 10 percent by weight carbon, theremainder of said powdered material being substantially iron basedpowder; compacting said mixture; and heat sintering said mixture abovethe melting temperature of the ferro titanium powder whereby the ferrotitanium melts and dissolves available carbon in the surrounding matrixto form titanium carbide particles.

1 1. The metal part of claim 10 wherein said ferro titanium powder priorto heat sintering has a mesh size of 40 or less.

12. The metal part according to claim 10 wherein said ferro titaniumpowder prior to heat sintering has a mesh size of 325 or less. 1

13. The metal part according to claim 10 wherein said mixture containscarbon in the range of about 0.5 to 1.5 percent by weight and ferrotitanium in the range of about 1.0 to 10 percent by weight.

14. The metal part according to claim 10 wherein said compacted mixtureduring sintering is maintained at or above 2,000F. for a period ofapproximately one hour.

15. The metal part of claim 10 wherein said compacted mixture isgradually heated to about 2,100F. for a period of about one hour;gradually cooled to about 825F. over a period of about three hours andthen cooled to ambient temperature.

16. The metal part according to claim 10 wherein said compacted mixtureis heat sintered to at least approximately 2,000F.

17. The metal part according to claim 10 wherein said compacted mixtureis heat sintered to at least 2,l00F.

18. The metal part according to claim 17 wherein said compacted mixtureduring sintering is maintained at or above 2,l00F. for a period ofapproximately 1 hour.

1. THE METHOD OF FORMING A METAL PART COMPRISING THE STEPS OF: PREPARINGA MIXRURE OF POWDERED MATERIAL HAVING ABOUT 0.25 TO 60 PERCENT BY WEIGHTFERRO TITANIUM AND ABOUT 0.1 TO 10 PERCENT BY WEIGHT CARBON THEREMAINDER OF SAID POWDERED MATERIAL BEING SUBSTANTIALLY IRON BASEDPOWDERED; COMPACTING SAID MIXTURE AND HEATS SINTERING SAID MIXTURE ABOVETHE MELTING TEMPERATURE OF THE FERRO TITANIUM POWDERED WHEREBY THE FERROTITANIUM MELTS AND DISSOLVES AVAILABLE CARBON IN THE SURROUNDING MARTIXTO FORM TITANIUM CARBIDE PARTICLES.
 2. The method according to claim 1wherein said ferro titanium powder prior to heat sintering has a meshsize of 40 or less.
 3. The method according to claim 1 wherein saidferro titanium powder prior to heat sintering has a mesh size of 325 orless.
 4. The method according to claim 1 wHerein said mixture containscarbon in the range of about 0.5 to 1.5 percent by weight and ferrotitanium in the range of about 1.0 to 10 percent by weight.
 5. Themethod according to claim 1 wherein said compacted mixture duringsintering is maintained at or above 2,000*F for a period ofapproximately one hour.
 6. The method according to claim 1 wherein saidcompacted mixture is heat sintered to at least 2,100*F.
 7. The methodaccording to claim 6 wherein said compacted mixture during sintering ismaintained at or above 2,100*F for a period of approximately one hour.8. The method according to claim 1 wherein said compacted mixture isgradually heated to about 2,100*F over a period of about 2 hours;maintained at about 2,100*F for a period of about 1 hour; graduallycooled to about 825*F over a period of about 3 hours and then cooled toambient temperature.
 9. The method according to claim 1 wherein saidcompacted mixture is heat sintered to at least approximately 2,000*F.10. A metal part comprising titanium carbide particles with a hardnessof 70 or more on the Rockwell C scale and formed by the steps of:preparing a mixture of powdered material having about 0.25 to 60 percentby weight ferro titanium and about 0.1 to 10 percent by weight carbon,the remainder of said powdered material being substantially iron basedpowder; compacting said mixture; and heat sintering said mixture abovethe melting temperature of the ferro titanium powder whereby the ferrotitanium melts and dissolves available carbon in the surrounding matrixto form titanium carbide particles.
 11. The metal part of claim 10wherein said ferro titanium powder prior to heat sintering has a meshsize of 40 or less.
 12. The metal part according to claim 10 whereinsaid ferro titanium powder prior to heat sintering has a mesh size of325 or less.
 13. The metal part according to claim 10 wherein saidmixture contains carbon in the range of about 0.5 to 1.5 percent byweight and ferro titanium in the range of about 1.0 to 10 percent byweight.
 14. The metal part according to claim 10 wherein said compactedmixture during sintering is maintained at or above 2,000*F. for a periodof approximately one hour.
 15. The metal part of claim 10 wherein saidcompacted mixture is gradually heated to about 2,100*F. for a period ofabout one hour; gradually cooled to about 825*F. over a period of aboutthree hours and then cooled to ambient temperature.
 16. The metal partaccording to claim 10 wherein said compacted mixture is heat sintered toat least approximately 2,000*F.
 17. The metal part according to claim 10wherein said compacted mixture is heat sintered to at least 2,100*F. 18.The metal part according to claim 17 wherein said compacted mixtureduring sintering is maintained at or above 2,100*F. for a period ofapproximately 1 hour.